Few people watching the exchanges in the House of Commons yesterday between representatives of the Big Six energy companies and MPs can have been enlightened by the confrontation. Those who consider the financial practices of the gas and electricity giants to be too opaque will have had their suspicions confirmed: it is simply impossible for most people to navigate through this bewildering world of tariffs, therms and gigawatts-per-hour. On the other hand, the energy bosses made a good fist of defending themselves, insisting that average profit margins were a modest 5 per cent and that price rises were due to matters outside their control, such as wholesale costs and government green levies. In addition, they needed to make money in order to invest in new infrastructure – and their healthy balance sheets are an important component of many pension funds.

Unfortunately, the temptation for grandstanding proved too great for some MPs to resist, with unsubstantiated accusations of profiteering and dark warnings that the elderly face a choice between heating and eating this winter. “We are not giving you guys a hard time for nothing,” said one Labour MP, revealingly. But this was not meant to be a kangaroo court, even if many hard-pressed consumers might have enjoyed the discomfiture of the executives. It was supposed to be a forum for uncovering whether – and why – the former nationalised utilities still exhibit monopolistic tendencies; and in that, it failed.

Perhaps it was something to do with the vertical integration of the businesses, whereby the retail side buys its energy from its own generating arm? No, said the bosses: we run them as separate businesses and don’t cross-subsidise. We also have lower prices than many EU countries, they added. The most interesting contribution, and certainly the most illuminating, came from Stephen Fitzpatrick, the chairman of Ovo Energy, a much smaller player trying to compete with the Big Six’s massive market share. He persuasively challenged their claims to operate in a competitive market. If that were true, how were they able to stop people switching supplier by immediately offering to cut their bills? Why does the price vary so much depending on the tariff? Only greater competition will bring down prices, said Mr Fitzpatrick; and yet the regulator Ofgem was failing in its duty to impose it.

David Cameron has promised a review of competition in the market – but the only way to sort this out is for the Competition Commission to test the defences of the Big Six and the counter-claims of informed (albeit not impartial) observers such as Mr Fitzpatrick. Once that happens, the rest of us might finally find out what is really going on.